Statistical Analysis: Based upon our prior experience approximately a third of the T1D subjects will have a MP index of less that 1.5 to direct compare to the invasive measured flow reserve. This maybe treated as a binary variable or as a continuous variable by combining all T1D subject compared to the non-DM control subjects. Data will be analyzed using unpaired t-test, linear and logistic regression. Continuous variables are expressed as mean ± standard deviation (SD) and are compared across groups by use of unpaired t-tests. All statistical analysis will be performed using two-sided tests with p < 0.05 considered statistically significant.